Sphene, magnetite and ilmenite. Glen Gairn, Scotland
125µm
A diorite has euhedral rhombs of sphene (light grey with brown internal reflections, centre left) showing faint zoning (top left) and associated with oxidized subhedral magnetite (light brown, centre). Anhedral ilmenite (brown, bottom left) occurs within biotite. One crystal of ilmenite has a sphene rim (blue-grey, centre bottom) which has a lower reflectance than euhedral sphene. The silicate matrix is biotite (bottom left) and feldspar (faint internal reflections, bottom right).
Polished thin section, plane polarized light, x 160, oil
